As shown in U.S. Pat. No. 6,030,581, an optical disc can be used to perform assays on biological or chemical samples. A sample can be provided in an opening and then moved by centrifugal force from one chamber or area to another chamber or area until it reaches an assay region where the sample (or a characteristic of the sample) can be observed.
As shown in U.S. Pat. No. 5,892,577, which also is incorporated herein by reference, a beam can be scanned over a rotating disc. Radiation reflected from and/or transmitted through the disc can be detected by a detector and used to read encoded information and/or detect assays.